Inkjet printers are efficient, quite and produce high quality print images in a relatively inexpensive manner when operated in low speed printing modes. Such quality is achieved by sweeping a large number of inkjet nozzles over a print medium and ejecting droplets of black ink onto the medium in one or more matrix arrays of minute ink drop patterns. Such arrays are known as swaths and the individual ink droplets are defined as pixels. The quality of the print image is then determined by assuring that each ink droplet has a precise volume of ink that is applied to a specific location on the print medium without smearing.
While such low speed inkjet printers have been satisfactory for many applications, there has been a constant demand for higher speed printers that produce high quality full color images. Meeting the demand for higher throughput while producing high quality, high ink density images however, has not been achieved easily. In this regard, in order to produce full vibrant colors on a print medium, large volumes of ink must be deposited in concentrated areas on the medium under proper environmental conditions. Failure to observe the proper environmental conditions relative to media and ink types may cause unwanted and undesired color degradation, ink smearing, and other undesired and unwanted hue shifts particularly at lower operating ambient temperatures.
One attempt at providing a satisfactory solution for printing high quality graphic images at a high throughput rate is disclosed in the Arbeiter et al. Patent (U.S. Pat. No. 5,608,439). The Arbeiter patent discloses a densitometer for adaptive control of ink drying time where a printer controller and an associated algorithm establish a variable delay time between sweeps. In this regard, the algorithm determines the maximum density of ink to be deposited in a given swath to control the amount of delay time between sweeps. In this manner rather than having a fixed delay time between individual sweeps, a variable delay time is implemented. This technique improves throughput but requires large amounts of processor time.
Although establishing a variable delay time between sweeps is an efficient method for improving throughput the disclosed technique does not consider the effects of ambient temperature on deposited ink droplets relative to different types and kinds of printing medium.
Therefore it would be highly desirable to have a new and improved inkjet printer and method that optimizes printing modes based upon the effects of ambient temperature on deposited ink droplets relative to different types and kinds of printing medium.
Another attempt at providing a satisfactory solution to avoiding ink smearing is disclosed in U.S. Pat. No. 4,910,528. The '528 patent discloses an algorithm solution involving temperature and printing demands. In this regard, a first determination algorithm calculates the number of ink droplets that will be deposited on a given page. A resulting density number provides a direct indicator of the printing demand to be placed on the printer. A second temperature predictive algorithm, utilizes the printing demand calculations, to determine the temperature change in the print head. The temperature differential provides a direct indicator of whether the operation of the print head for the printing activity will remain within acceptable temperature limits. A final algorithm, using the temperature indicator calculations, causes one of several mutually exclusive strategy actions to be taken involving the printing rate, the time permitted for print head cooling without printing and the heating of the print head when the a beginning temperature level is below an acceptable minimum temperature.
While the utilization of a variable sweep delay time and print head thermal control procedures has been successful in many applications, it would be highly desirable to have a new and improved printer and method for improving full color print quality images having densely inked areas on various types of print media without inhibiting carriage movement between swaths and without the need of using a combination of complex predictive algorithms.